Question

1 、x+y=8 xy=6 求x²+3xy+2y²/x²y+2xy²

1 、x+y=8 xy=6 求x²+3xy+2y²/x²y+2xy²的值。

2、3/a=4/b=5/c,求分式 ab-bc+ac/a²+b²+c²的值

各位救命啊、明天要交的、解出一题也行

Answer 1

1 、x+y=8 xy=6 求x²+3xy+2y²/x²y+2xy²的值。
x²+3xy+2y²/x²y+2xy²
=(x+2y)(x+y)/xy(x+2y)
=(x+y)/xy x+y=8 xy=6
=8/6
=4/3

2、3/a=4/b=5/c,求分式 ab-bc+ac/a²+b²+c²的值
∵3/a=4/b=5/c,
∴b=4a/3
c=5a/3
∴ab-bc+ac/a²+b²+c²
=(a*4a/3-4a/3*5a/3+a*5a/3)/(a²+16a²/9+25a²/9)
=(4a²/3-20a²/9+5a²/3)/(50a²/9)
=(27a²/9-20a²/9)/(50a²/9)
=(7a²/9)/(50a²/9)
=7/50

Answer 2

1 、x+y=8 xy=6
x²+3xy+2y²/x²y+2xy²
=(x+y)(x+2y)/xy(x+2y)
=(x+y)/xy
=8/6
=4/3
2、
设3/a=4/b=5/c=k
a=3/k
b=4/k
c=5/k

分式 ab-bc+ac/a²+b²+c²
=（(3/k)*(4/k)-(4/k)*(5/k)+(3/k)*(5/k)）/((3/k)^2+(4/k)^2+(5/k)^2)
=（12/k^2-(20/k^2)+(15/k^2)）/(9/k^2+16/k^2+25/k^2)
=（7/k^2）/(50/k^2)
=7/50

Answer 3

x²+3xy+2y²/x²y+2xy²=(x+y)(x+2y)/xy(x+2y)=(x+y)/xy=4/3
3/a=4/b=5/c=k 则a=3/k b=4/k c=5/k代入求的7/50

Answer 4

1.x^2+3x+2y^2/x^2y+2xy^2
=(x+y)(x+2y)/xy(x+2y)
=(x+y)/xy
=8/6
=4/3